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Pheochromocytoma Presenting with Hyperglycemia, Polyuria, and Polydipsia

Saturday, October 20, 2012
Grand Oaks Mansion (Mardi Gras World)
Saranya Srinivasan, M.D. and Amanda Growdon, M.D., Medicine, Children's Hospital Boston, Boston, MA

Case Report:

A 14-year-old female was referred to the Emergency Department (ED) with hyperglycemia concerning for new onset diabetes mellitus. She had influenza-like symptoms including low-grade fevers, fatigue, and myalgias approximately 5 weeks prior to presentation. Shortly after, she developed polyuria, polydipsia, and polyphagia and experienced a 10-pound weight loss over 5 weeks.  She also reported episodes of tachycardia and diaphoresis with intermittent headaches. Initial work-up at her pediatrician's office included a negative Monospot and normal thyroid function studies. On the day of presentation, the patient's blood glucose was found to be 280 mg/dL and her urinalysis demonstrated glucosuria with trace ketones. On arrival to the ED, her blood glucose had normalized to 89 mg/dL and her urinalysis was negative for glucose and ketones. Hemoglobin A1C returned at 5.9 %. Her initial blood pressure was 90/54 but while in the ED, she became tachycardic, diaphoretic, and acutely hypertensive to 192/144. She was admitted to the Intensive Care Unit. Ophthalmologic examination demonstrated Grade IV hypertensive retinopathy. Urine metanephrines and normetanephrines were found to be significantly elevated. Nuclear medicine MIBG scan demonstrated intense radiotracer uptake within the left adrenal gland (Figure 1) and abdominal MRI demonstrated a 3.9 centimeter left adrenal mass, consistent with a pheochromocytoma without malignant features (Figure 2). The patient underwent surgical resection, confirming the diagnosis of pheochromocytoma. The patient has had no further recurrence of her tumor two years out. 

Discussion:

Pheochromocytoma, a catecholamine-secreting adrenal tumor that occurs in both children and adults, is a very rare cause of hypertension in children, accounting for less than 1% of cases.  Pheochromocytoma classically presents with episodic headaches, diaphoresis, and tachycardia; however, these symptoms are only present in approximately 50% of adult patients with this diagnosis. Children often present with sustained hypertension along with nonspecific symptoms such as abdominal pain or distension. Malignant hypertension has also been reported. Other less common symptoms include weight loss, polyuria, and polydipsia, all of which can mimic Type I diabetes mellitus.  Hyperglycemia and impaired glucose tolerance have been reported in up to 75% of patients with pheochromocytoma. Hyperglycemia is thought to be secondary to both decreased insulin secretion and insulin resistance due to catecholamine release. While hyperglycemia is often seen with pheochromocytoma, true diabetic ketoacidosis is very rare and only several cases have been reported.  Given that several of the less common clinical manifestations of pheochromocytoma overlap with those of diabetes mellitus, clinicians should consider a broad differential diagnosis in patients with atypical presentations of hyperglycemia.

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Figure 1. Nuclear medicine MIBG scan demonstrating intense radiotracer uptake within the left adrenal gland, indicated by the red arrow.

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Figure 2.  Abdominal MRI demonstrating a 3.9 centimeter left adrenal pheochromocytoma, indicated by the red arrows.